This invention relates generally to surgical devices, and has particular reference to an improved intramedullary bone-setting assembly. The bone setting assembly of the invention is adapted to be inserted in the intramedullary passage of the two parts of an elongated broken bone, such as an arm or leg bone. The insertion is made through an incision in the limb at the break, and the purpose of the assembly is to align the broken parts of the bone and to prevent rotation or torsion of one part with respect to the other.
Prior art bone-setting devices either have exterior plate members secured to the bone parts by pins or screws which injure the flesh and muscle surrounding the bone or have similar transversely extending fastening devices through the bone which weaken the hard outer layer of the bone. Other devices must be inserted from one end of the bone and then removed after the fracture has healed. Still other devices keep the parts of the bone on either side of the fracture in alignment but do not prevent rotation of one bone part about the bone axis with respect to the other part. Such devices require immobilizing casts or other restraining means which must be worn for a considerable length of time to prevent torsional movement of the bone parts.
The closest prior art known to the applicants is their own U.S. Pat. No. 4,016,874 granted Apr. 12, 1977 for a Three-Part Intramedullary Bone-Setting Pin. The device disclosed by this patent comprises a pair of tubular parts that are threaded into the respective parts of a broken bone and a central connecting and aligning pin that, in finally assembled form, is positioned in the tubular parts with approximately half its length in each. The pin and interior passages of the tubular parts are preferably square in cross section so that relative rotation between the parts is prevented. A disadvantage of this prior device is the need for threading the tubular parts into the respective bone parts.
Other prior art developed in searches made subsequent to the grant of U.S, Pat. No. 4,016,874 is disclosed in U.S. Pat. Nos. 3,986,504; 4,024,531; 4,091,806; 4,187,841; 4,227,518; 4,237,875 and 4,275,717.